I finally caved and bought NARS Douceur recently. NARS Douceur is a very 'me' sort of blusher, it's a pinky brown shade that adds a little colour and acts to sculpt the cheeks. I had hesitate over buying this colour before as it's quite similar to several blushers that I already own. I have included a comparison below to show you exactly what I mean about the similarity.
Douceur is a neutral pinky brown and has a satin finish, if it catches the light in just the right way you will see tiny flecks of microshimmer (you can see this if you enlarge the pictures above). The microshimmer isn't visible on the cheeks but the tiny amount of shimmer stops it looking completely flat. It's not as densely pigmented as my other NARS blushers, as I discovered when swatching, but I can't say I had any issues with the colour when applying. The effect with this sort of blusher is subtle and acts a bit like contouring. I often favour these sorts of colours as they pair well with practically any eye look or lipstick shade.
When I compared Douceur to my other similar blushers I was happy to see none are exact dupes. However, I wouldn't say you need all of these colours unless you are a bit pinky-brown obsessed like me! The swatches shown are heavy application, with three or four passes of the pan to build up the colour. MAC Prim & Proper was a limited edition colour from the Give Me Liberty of London collection, this shade is the warmest and most tan colour of the bunch. Douceur appears to pull more brown than MAC Cubic, which I think looks like a dusty pink in comparison. RBR Delicata is the lightest of the four and is probably more beige-pink when compared to the others.
I enjoy wearing all of these blushers but find Prim & Proper is probably the most neglected. If you're nervous of blusher or you're looking for something to give a subtle colour to the cheeks, I would happily recommend Douceur, Cubic or Delicata. All three are easy to wear in terms of both colour and finish.